Known acoustic wave touch panels have included a substrate and X and Y axis transmitting transducers mounted thereon to impart acoustic waves for propagation in the substrate. The acoustic waves imparted into the substrate are reflected, by respective X and Y axis reflective arrays, along a number of substantially parallel paths that extend across a touch area of the substrate to second, respective X and Y axis reflective arrays. These latter arrays reflect the acoustic waves incident thereto to respective X and Y receiving transducers mounted on the substrate. Other known acoustic touch panels utilize only one transceiving transducer and one associated reflective array per axis. More particularly, each of these transducers functions to impart an acoustic wave into the substrate for reflection by an associated array along a number of substantially parallel paths across the touch surface of the panel to a reflective edge of the substrate or a reflective grating disposed therein. The reflective edge or grating reflects the acoustic waves incident thereto back across the touch surface of the panel to the associated reflective array which in turn reflects the waves back to the transducer for sensing.
Controllers are provided for these types of acoustic wave touch panels for generating drive signals to be applied to the X and Y axis transmitting transducers; for receiving and amplifying the X and Y axis sense signals from the transducers; and for determining the coordinate of a touch on the panel from the respective X and Y axis sense signals. Heretofore known touch panels have included gates, switches or the like disposed between the transducers and the amplifier stages of the controller to prevent signals from both the X and Y axis transducers from being simultaneously received. More particularly, these controllers operate to first apply a burst drive signal to one of the transmitting transducers, the X axis transducer for example. Then the controller controls the gate or switch to couple the signal received from only the X-axis transducer to an amplification stage. After the X-axis signal is processed, the controller applies a burst drive signal to the Y-axis transducer and thereafter switches the gate to couple the signal received from only the Y axis transducer to the amplification stage. The gate to prevent the X axis and Y axis transducer signals from being received simultaneously, was thought necessary to obtain signals from which touch coordinates could be obtained. This is because it was thought that when acoustic waves were imparted into the substrate from one axis, spurious waves would be picked up by the transducer associated with the other axis. It was thought that the spurious acoustic waves would result in a transducer sense signals of sufficient magnitude to prevent the simultaneous receipt and processing of the X-axis and Y-axis signals. However, it has further been found that the position of the gate or switch with respect to the amplifier stage creates great problems with noise to make processing of the sense signals and recognition of a touch from the received sense signals difficult.